Mangrove pneumatophores as biocatalysts for the fabrication of silver nanoparticles and their potential applications against biofilm formation and hepatic carcinoma

The current study demonstrates the biogenic synthesis of silver nanoparticles using the pneumatophores of Acanthus ilicifolius (AiP-AgNPs), which is cost-effective and biocompatible. A. ilicifolius possesses remarkable features to endure the harshest conditions for its entire life cycle and generates secondary metabolites for its sustainability in hostile mangrove ecosystems. The presence of a prominent UV-visible absorption band at 420 nm supported the distinct color change inference for the synthesized AiP-AgNPs. The size of the synthesized AiP-AgNPs was determined to be ∼15 nm through field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (cryo-TEM), and atomic force microscopy (AFM). The presence of secondary metabolites such as 2-bromo-1,1-dichloroethene, hemin and N-(sulfanylacetyl)-L-seryl-L-argininamide was indicated by prominent peaks in liquid chromatography, suggesting their probable roles in the synthesis of AgNPs. The synthesized AiP-AgNPs demonstrated a distinct zone of inhibition against Pseudomonas aeruginosa (15.33 mm), Vibrio cholerae (9.83 mm), and Bacillus subtilis (12 mm). They also exhibited concentration-dependent antioxidant activity in DPPH, nitric oxide, and hydrogen peroxide scavenging assays. The anticancer potential of the synthesized AiP-AgNPs against HepG2 hepatocarcinoma cells determined through MTT colorimetric assay and flow cytometry revealed their dose-dependent cytotoxicity with the occurrence of the sub-G₀ phase (25.6%). Subsequent analysis using fluorescence microscopy, DNA damage, comet assay, and migration assay indicated that AiP-AgNPs hold significant potential and the ability to serve as a therapeutic candidate to pave the way for further in-depth investigations for pre-clinical and clinical research purposes.